This invention relates to apparatus for molding a self-hardening material such as concrete and for efficiently producing molded concrete articles or the like. In general, such apparatus is disclosed in U.S. Pat. Nos. 3,303,545, 3,624,825 and 4,068,996 which issued to applicant. In such molding apparatus, an elongated mold box is supported for tilting movement between a vertical concrete filling position and a horizontal article stripping position. When the mold box is in the vertical position, mixed concrete is delivered from a hopper to the top open end of the mold box which contains a pallet. The concrete is conveyed into the mold box while the mold box is vibrated and until the mold box is filled. The mold box is then tilted to a horizontal position where the molded concrete article is supported by the pallet within the mold box and where the concrete article is stripped from the mold box onto a horizontal run-out table or platform while the article continues to be supported by the pallet.
In the construction of the above equipment or apparatus for molding large rectangular concrete panels or slabs, it is desirable to avoid the construction of a pit within the ground or floor for receiving the mold box when it is tilted to a vertical filling position, for example, as disclosed in above U.S. Pat. No. 3,624,825. As disclosed in above U.S. Pat. No. 4,068,996, the construction of a pit may be avoided by pivotally supporting the mold box at one end. However, when the mold box is relatively large and the mold box cavity is filled with concrete, substantially large hydraulic cylinders are required to pivot the mold box, and substantial stresses are encountered in the cantileverly supported mold box.
In the construction of the molding apparatus shown in the above patents, it has also been found that the fabricated rectangular pallets receive significant wear when they are moved in and out of the mold box, and this limits the reusable life of each pallet. It has also been found desirable to provide for withdrawing each pallet from the mold box onto the run-out table or platform along a precise linear path. When the molded concrete article is precisely stripped from the mold box, damage to the molded concrete article is reduced, and scrap molded articles is minimized. The need for precision stripping of the molded article from the mold box cavity is particularly important when molding long rectangular concrete articles such as the concrete slabs or panels shown in the above patents since the articles are stripped longitudinally from the mold box.